1. Field Of The Invention
The present invention relates to a transmission control system for an ATM network wherein the call set up and the connection set up are separate.
2. Description Of The Related Art
At present B-ISDN (Broad-band Integrated Service Digital Network) is being examined as next generation transmission technology and ATM (Asynchronous Transfer Mode) is being considered for use as transmission exchange technology with B-ISDN. In this ATM exchange technology, data such as audio or pictures is transferred as fixed length packets known as cells. The bands therefore have to be divided in a fixed manner corresponding to the amount of information, which proved to be difficult using conventional STM (Synchronous Transfer Mode) systems. New technology is therefore desired where information such as picture information will undergo instantaneous expansion in a transfer process.
Also, even with ATM exchange technology call set up procedures already exist. This is to say that call and connection routes can be established from a transmission node (transmission exchange) to a receiving node (receiving exchange) via a plurality of relay nodes (relay exchanges) by sequentially linking between stages, which is known as "link by link" connecting. Although the transmission speed once the connection has been made is sufficiently fast with this system, it takes a long time to actually establish the connection in the first place.
ATM networks have to be able to handle large amounts of information transmitted over short periods of time i.e. what are known as information "bursts". So, depending on the information, it is necessary to select a route which will keep the number of lost cells to a minimum (routes with large bandwidths) while taking into account the fact that the call set up and connection set up routes must be different.
As this invention sets out to solve the problems encountered in the related art, its purpose is to provide a control system which carries out call set ups at high speeds while keeping call and connection paths separate.